48,150 research outputs found
Evolution of Magnetic and Superconducting Fluctuations with Doping of High-Tc Superconductors
Electronic Raman scattering from high- and low-energy excitations was studied
as a function of temperature, extent of hole doping, and energy of the incident
photons in Bi_2Sr_2CaCu_2O_{8 \pm \delta} superconductors. For underdoped
superconductors, short range antiferromagnetic (AF) correlations were found to
persist with hole doping, and doped single holes were found to be incoherent in
the AF environment. Above the superconducting (SC) transition temperature T_c,
the system exhibits a sharp Raman resonance of B_{1g} symmetry and energy of 75
meV and a pseudogap for electron-hole excitations below 75 meV, a manifestation
of a partially coherent state forming from doped incoherent quasi particles.
The occupancy of the coherent state increases with cooling until phase ordering
at T_c produces a global SC state.Comment: 6 pages, 4 color figures, PDF forma
Scattering Rule in Soliton Cellular Automaton associated with Crystal Base of
In terms of the crystal base of a quantum affine algebra ,
we study a soliton cellular automaton (SCA) associated with the exceptional
affine Lie algebra . The solitons therein are labeled
by the crystals of quantum affine algebra . The scatteing rule
is identified with the combinatorial matrix for -crystals.
Remarkably, the phase shifts in our SCA are given by {\em 3-times} of those in
the well-known box-ball system.Comment: 25 page
Separable states and the geometric phases of an interacting two-spin system
It is known that an interacting bipartite system evolves as an entangled
state in general, even if it is initially in a separable state. Due to the
entanglement of the state, the geometric phase of the system is not equal to
the sum of the geometric phases of its two subsystems. However, there may exist
a set of states in which the nonlocal interaction does not affect the
separability of the states, and the geometric phase of the bipartite system is
then always equal to the sum of the geometric phases of its subsystems. In this
paper, we illustrate this point by investigating a well known physical model.
We give a necessary and sufficient condition in which a separable state remains
separable so that the geometric phase of the system is always equal to the sum
of the geometric phases of its subsystems.Comment: 13 page
Probing Majorana neutrinos in rare K and D, D_s, B, B_c meson decays
We study lepton number violating decays of charged K, D, D_s, B and B_c
mesons of the form M^+\to {M'}^-\ell^+\ell^+, induced by the existence of
Majorana neutrinos. These processes provide information complementary to
neutrinoless double nuclear beta decays, and are sensitive to neutrino masses
and lepton mixing. We explore neutrino mass ranges m_N from below 1 eV to
several hundred GeV. We find that in many cases the branching ratios are
prohibitively small, however in the intermediate range m_\pi < m_N < m_{B_c},
in specific channels and for specific neutrino masses, the branching ratios can
be at the reach of high luminosity experiments like those at the LHC-b and
future Super flavor-factories, and can provide bounds on the lepton mixing
parameters.Comment: 25 page
Origins of the Isospin Violation of Dark Matter Interactions
Light dark matter (DM) with a large DM-nucleon spin-independent cross section
and furthermore proper isospin violation (ISV) may provide
a way to understand the confusing DM direct detection results. Combing with the
stringent astrophysical and collider constraints, we systematically investigate
the origin of ISV first via general operator analyses and further via
specifying three kinds of (single) mediators: A light from chiral
, an approximate spectator Higgs doublet (It can explain the
anomaly simultaneously) and color triplets. In addition, although from an
exotic mixing with generating , we can combine it with
the conventional Higgs to achieve proper ISV. As a concrete example, we propose
the model where the charged light sneutrino is the inelastic
DM, which dominantly annihilates to light dark states such as with sub-GeV
mass. This model can address the recent GoGeNT annual modulation consistent
with other DM direct detection results and free of exclusions.Comment: References added and English greatly improve
Efficiency of Nonlinear Particle Acceleration at Cosmic Structure Shocks
We have calculated the evolution of cosmic ray (CR) modified astrophysical
shocks for a wide range of shock Mach numbers and shock speeds through
numerical simulations of diffusive shock acceleration (DSA) in 1D quasi-
parallel plane shocks. The simulations include thermal leakage injection of
seed CRs, as well as pre-existing, upstream CR populations. Bohm-like diffusion
is assumed. We model shocks similar to those expected around cosmic structure
pancakes as well as other accretion shocks driven by flows with upstream gas
temperatures in the range K and shock Mach numbers spanning
. We show that CR modified shocks evolve to time-asymptotic states
by the time injected particles are accelerated to moderately relativistic
energies (p/mc \gsim 1), and that two shocks with the same Mach number, but
with different shock speeds, evolve qualitatively similarly when the results
are presented in terms of a characteristic diffusion length and diffusion time.
For these models the time asymptotic value for the CR acceleration efficiency
is controlled mainly by shock Mach number. The modeled high Mach number shocks
all evolve towards efficiencies %, regardless of the upstream CR
pressure. On the other hand, the upstream CR pressure increases the overall CR
energy in moderate strength shocks (). (abridged)Comment: 23 pages, 12 ps figures, accepted for Astrophysical Journal (Feb. 10,
2005
Polarization immunity of magnetoresistivity response under Microwave excitation
We analyze theoretically the dependence of the microwave polarization sate
and sense on the magnetoresistivity response of two-dimensional electron
systems. Linear and circular polarization have been considered with different
senses and directions. We discuss the polarization dependence of the
longitudinal magnetoresistivity and propose an explanation for the
experimentally observed polarization immunity, i.e., resistivity oscillations
and zero resistance state regions are unaffected by the sense of circular
polarization or by the direction of microwave electric field.Comment: 4 pages and 1 figur
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